Holidaymakers are bracing for long queues at borders as additional checks are carried out and international travel increases after quarantine measures are eased.
Transport Secretary Grant Shapps warned on Friday that people should “expect more disruption than usual” due to coronavirus-related inspections.
Travel firms reported accelerated bookings after the Government announced that double-jabbed Britons and under-18s will be exempt from quarantine measures when returning to England from amber list countries from July 19.
Mr Shapps said ministers are “actively working” on accepting vaccination certificates from other countries after it emerged only passengers with NHS-issued jabs would be exempt.
He added that most of the queuing will be before departure back to England, with airlines checking passenger locator forms, and whether travellers have taken a pre-departure test and booked a post-arrival test.
“So the place to expect queues is the airport you are coming from. Once you get back to the UK all of that is starting to be automated,” he told BBC Breakfast.
“People should expect more disruption than usual but I know that everyone is working very hard to minimise those queues.”
But the Immigration Services Union representing border staff warned of delays because, while electronic gates are being adapted, “not all of them are available and not everywhere”.
Spokeswoman Lucy Moreton said peak queues are currently up to two hours and could increase to six hours with the Covid inspections, which must be carried out by UK border staff regardless of airline checks, taking around three times longer.
“It’s a political decision to check 100% of Covid arrivals and that largely is the problem here,” she told BBC Radio 4’s Today programme, warning of more staffing shortages before self-isolation rules are changed for double-jabbed coronavirus contacts.
“There still will be queues associated with EU exit, with staff perhaps not being as available particularly if self-isolation figures surge in the way people are suggesting they might do before August 19.
“But whilst we retain the requirement to check four pieces of documentation for every arriving passenger – the e-gate cannot check the pre-departure test certificate because they’re not uniform, and they can’t at the moment check any vaccination status, if that becomes relevant – so whilst that remains the political imperative these queues are going to happen.”
The plans mean people travelling back from amber list countries, such as France, Spain and Portugal, can travel as freely as from green list countries if they have been double-jabbed.
But currently those vaccines must have been administered by the NHS.
Mr Shapps told Sky News: “The next thing is to be able to recognise apps from other countries or certification from other countries.
“It is easier done from some places, like the EU where they have a digital app coming along, than it is in the United States where I think they have 50 different systems, one for each state.”
Travel firm Skyscanner said that 30 minutes after Thursday’s announcement on the amber list easing there was a 53% increase in searches in the UK compared with a day earlier.
Northern Ireland is likely to follow the change from July 26, while Scotland and Wales are considering whether to adopt the same rules.